Australian abbreviation for fizz-gig. A police informer. Usually a petty criminal who informs on others to the police in return for payment, or a reduction in penalty when he is caught committing a crime himself. Sometimes shortened to gig.

Imreckon that Bob is a fizz-gig. I saw him talking to two drug squad cops last night.

I think Bob fizzed on Tom because those cops then went to ztom's house and arrested him for drugs.